Orthogonal Frequency Division Multiplexing (OFDM for short) technology is able to convert data streams transmitted at a high speed to data streams transmitted at a low speed and in parallel, and thereby, is able to reduce the sensitivity of a system towards frequency selectivity of a multi-path fading channel.
The OFDM technology is further improved on the ability of resisting intersymbol interference, by introducing a cyclic prefix into the OFDM technology.
Currently, with the features such as high bandwidth utilization rate and easy implementation, the OFDM technology has been more and more widely used in the field of wireless communications. Worldwide Interoperability for Microwave Access (WiMAX for short) system based on Orthogonal Frequency Division Multiple Access (OFDMA for short) is a system using the OFDM technology.
Meanwhile, with the development of communication technology, the mobile WiMAX system based on IEEE802.16e air interface standard cannot satisfy users' requirements for high transmission rate, high throughput, fast moving and low delay in broadband mobile communications.
Currently, Task Group m (TGm for short) of IEEE802.16 group is dedicated to making an improved air interface specification 802.16m, and the specification can support higher peak rate and higher spectral efficiency and sector capacity.
In order to satisfy the effective application of low-delay service in the 16m system, a three-layer design idea of super frame, unit frame and subframe are mainly taken into account in the current design of the 16m frame structure, wherein the structure of the three-layer design can be obtained by referring to FIG. 1.
As shown in FIG. 1, in the super frame structure proposed in the current 16m frame structure design, super frame 101 has a length of 20 ms, and is composed of four unit frames 102 of 5 ms. Super frame control information 103 is in several symbols at the beginning of a super frame. Unit frame 102 is composed of eight subframes 104, and the subframes 104 are divided into downlink subframes and uplink subframes, which can be configured according to the system. The subframe 104 is composed of 6 OFDM symbols 105.
On the basis of such three-layer frame structure of super frame, unit frame and subframe, a 16m terminal cannot acquire in advance the setting information of the control information in a unit frame, and as a result, when receiving the unit frame, the 16m terminal needs to open all of the radio frequency transmissions to acquire the control information in the unit frame, which increases the power consumption of the 16m terminal.